CTSL and esophageal squamous cell carcinoma: Zhenhu Zhang’s study demonstrated significantly higher expression levels of CTSL in ESCC tissues than adjacent non-cancerous tissues (Zhang et al., 2024); Shengnan Zhao’s research revealed increased cathepsin B levels in colonic tissue and exacerbated dextran sodium sulfate (DSS)-induced colitis (Zhao et al., 2016).